#include<iostream>
using namespace std;

int main(){
    int n; cin >> n;
    long long int ans=1,p;
    for(int i=0;i<n;i++){
        cin >> p;
      	if(p==0){cout << 0 << endl; return 0;}
        ans = (ans * (p%9))%9;
    }
  if(ans==0) cout << 9 << endl;
  else  cout << ans << endl;
}